83 300SD

I've had a lousy idle for a long time. Replacing the rack dampener and upping the idle speed to 800 helped, but it was still lumpy. The past couple of weeks, it was getting harder and harder to start. My glows aren't working, but they haven't been working for a while and I've not had trouble starting until the past couple weeks (90+ degrees lately).

Yesterday evening, I replaced the spin-on filter (filled it with Sea Foam), the car started, but immediately died and hasn't started since. I've bled the lines at the injectors and have no air in the system.

After talking with a mechanic familiar with Benz diesels, here's what he says happened: He says there's a governor spring in the IP that, over time, got weak and yesterday finally broke when the pump lost it's prime after changing the filter. He says this spring - NOT the rack dampener but a spring internal to the IP - gets weak and, as it weakens, retards the timing, making starting difficult. When it breaks, it makes starting impossible.

I've had the car towed to this fellow's shop. He's gonna pull the IP, replace the spring, reinstall and retime the thing, and replace the glows. My bill, he says, should be about $300.

He says this is a common problem, but I can find nothing online about it.

Does this sound plausible and fair?

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

I haven't read about that problem on this forum. That's not to say the mechanic is not correct. If he is, it's information we need to consider on the forum. Some pictures of the broken spring during the repair process might be useful.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'll ask the mechanic to take pix as he goes and will even offer up a camera to borrow. I would like pix myself to see what 35,000 of vegetable oil blends have done to the innards of the IP.

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

If you are careful filter and de-watering it should fine. If not, then I bet you will find rust and gunk.

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1983 123.133 California
- GreaseCar Veg System

I just looked at an exploded view of the IP, there are two springs in there, both referred to as compression springs. I'll agree with kerry, the forum should be made aware of something along these lines as being a common failure.

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83 SD

84 CD

UPDATE: Mechanic said it's not the pump. He found injectors locked up. But after new injector nozzles (pop tested right), new delivery valves, new glow plugs, new fuel (straight diesel), new filters, no air in the lines ... it still will not start. The mechanic has forced it to start and reports that it runs well if the RPMs are over 1100, but as soon as the throttle is released it shuts down.

I've been a week and a half without my car, burning up the diesel in my big Dodge and racking up the bill on the Benz. I feel like I'm about to puke.

Can anyone give me a clue?

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

Compression test? Also, what condition are the pre chambers in?

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gotta say this runs up a little red flag... "He says there's a governor spring in the IP that, over time, got weak and yesterday finally broke when the pump lost it's prime", Like Kerry said, thats a new one around here. Seems allot of the most "obscure" things pop up here over time, but not that, or did I miss it?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

How timely is this thread? Mine just gave up on me this week. I have the same symtoms except for the hard starting. Very rough idle with dead misses that aren't on a single cylinder. Ran great above idle though. I just bumped up my idle last weekend and thought its idling much better. I'm driving along and suddenly felt a loss of power then it got better then worse. It cycled like that loosing power every time until I could no longer go any further. It was still running but was missing badly and the throttle did little to change the idle. I've drained the tank and changed the filters and now trying to bleed out the bubbles. Realistically, the market is telling me I have maybe $1700 car. I can't justify a whole lot of $$$ chasing the problem. I enjoy this car so I'm willing to do the work myself if I had the correct tools. If its the pump I may be looking at a real nice parts car though.

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'83 300DT
'04 Forester XT--modified
'61 Beetle EFI Turbo
Burley recumbant

The consensus is that my IP is tired. It is working, but not building enough pressure to pop the injectors to start. In speaking with Matt at Old World Auto and another local Mercedes guy (who won't touch my car 'cause I've run it on WVO), this seems to be a common occurrence at the 30-35k mark on WVO, regardless of the system. He has a customer with the exact same symptoms who is running a heated two-tank system ("professional" grade). Mine is a heated single-tank blend.

So ... I'm in the market for an injection pump for my car. There's a couple of used one on ebay now for around $200. Does anyone have any better offers? I also need someone that can pull and replace an IP - the mechanic where it sits doesn't have the tools - he's more of an industrial/ag diesel tech.

And it looks like I'm gonna cancel my restaurants, use up what oil I have left at a very, very thin blend (like 50% or less) and go back to straight diesel. What money I've saved over the past 35k miles will be buying an IP.

With all that said, my IP has 265k on it. Perhaps it's just dying of old age and not a victim of WVO. My engine was rebuilt, but the IP just moved over.

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

My IP is going strong at 274K on Dino #2. I think that they're usually good for quite a bit more than that when used with straight diesel. Sorry to hear about the misfortune.

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1983 300SD
Rusty, Loud and Proud

There are no springs that control timing in this type of injection pump. There is an advance mechanism for injection timing but it's built into the drive sprocket that drives the pump.
Either the damn thing is getting fuel when it cranks or it's not. I'm beginning to wonder about this guy.

It's getting fuel but not putting out/holding enough pressure to pop the injectors. That's how I understand what he's telling me, anyway. Is that possible?

I'm frustrated and depressed. I miss my car. I miss the pride of running it on WVO - and I'm proud of my WVO system: Clean, dry oil blended no more than 80% in a system heated with the best available injection line heaters and a 26-plate heat exchanger.

I'm at a loss as to what to do. I don't have unlimited funds.

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1983 300SD, Silver/Blue, 230+K (rebuilt at 196K)

Doesnt make much sense to me. If you can, go the library and get a book on injector pumps for some good diagrams.
They are pretty simple things really. There is a small piston for each cyl inside the injection pump. when the piston is pushed upwards it displaces the fuel on top of it and the fuel is forced past the injector nozzle. That part of the pump works just like the master cyl in your brake system. When the piston moves the fluid has to move because it cannot be compressed.
If the engine ran at all I would say the rack is moving into the no fuel position below a certain rpm.

How about "delivery valve seals"??. On my 616s I would try replacing them.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"